1. Field of the Invention
The present invention relates to processing of seismic data obtained in surveys where multiple swept frequency vibratory sources are operating simultaneously in various sectors of an area of interest.
2. Description of the Related Art
Simultaneous sources or blended acquisition in seismic surveying can significantly improve the source productivity of seismic land and marine crews. Their purpose is to lead to well sampled seismic wavefields and improved seismic imaging. Recently, several field studies on source blended acquisition using vibratory sources have been conducted. The first land simultaneous source acquisition method proposed that each vibroseis fleet operate independently of one another using a stakeless guidance system. The method was referred to as an independent simultaneous sweeping field acquisition technique. The intent was to achieve a significant increase in acquisition efficiency coupled with superior image quality. One available service according to the independent simultaneous sweep method is that provided under the trademark ISS® of BP p.l.c. of the U. K.
Blended acquisition schemes are based on the randomization of source timings such that the cross-talk noise can be attenuated in different domains (i.e., common-receiver, common-offset and cross-spread) using random noise attenuation algorithms and workflows. Stacking and migrating the blended seismic data without any further noise removal or denoising produces acceptable results as stacking can effectively suppress random energy.
Statics is a major concern for simultaneous sources data as clear first-breaks are needed for the calculation. Static correction is a bulk shift of a seismic trace in time during seismic processing. A common static correction is the weathering correction, which compensates for a layer of low seismic velocity material near the surface of the earth. Other corrections compensate for differences in topography and differences in the elevations of sources and receivers. The solution of near surface statics requires accurate first break picking in the recorded trace data.